Open Saas provides a full-stack React and Node.js framework for building SaaS applications. It is open-source and free to use, with no vendor lock-in so the application can be deployed anywhere. Common SaaS features are pre-built and configured, such as authentication, payments integration via Stripe, email sending, file uploads, and an admin dashboard. Rapid development is supported through Wasp, a compiler that generates code for the frontend, backend, and deployment.